1. Field of the Invention
The present invention relates to a cassette loading device used for a magnetic recording/reproducing apparatus.
2. Description of the Related Art
Recently, among magnetic recording/reproducing apparatuses, videotape camera-recorders are becoming less expensive. Videotape camera-recorders, for example, include a cassette loading device for loading a cassette into the recorder.
A conventional cassette loading device will now be described below.
A conventional cassette loading device is disclosed in Japanese Laid-Open Patent Publication No. 11-213490, as shown in FIGS. 8A-8C which illustrate specific portions of the conventional cassette loading device. Although the aforementioned Patent Publication uses member names such as a “boss 20”, a “support pin (flange) 21”, and a “pin hole 17b”, these members are respectively referred to herein as a “support pin boss 20”, a “support pin 21”, and a “pin insertion hole 17b” and, as shown in FIG. 8C, reference numeral 22 is also used to denote a “support pin flange”.
FIG. 8A is a perspective view showing a portion of the conventional cassette loading device. FIG. 8B is a side view for explaining an insertion direction of the support pin 21. FIG. 8C is a cross-sectional view of the support pin 21. In FIG. 8A, the conventional cassette loading device includes a cassette holder 11 which receives a cassette (not shown). The cassette holder 11 has a flat box-like structure and receives a cassette from the right side of FIG. 8A.
The cassette holder 11 can be moved up and down whilst being kept horizontal by a holder retention mechanism including two pairs of arms 13 and 15. In FIG. 8A, although only one arm of each of the pair of arms 13 and 15 is shown, the other arm of the pair of arms 13 and 15 is provided on the opposite side of the cassette holder 11. The arms 13 and 15 are pivotably supported by a support pin 16. One end of the arms 13 and 15 is pivotably attached to a chassis sidewall 17 and a holder sidewall 11a, respectively. The other end of the arms 13 and 15 is supported by support pins 12 and 21 so as to be in communication with the holder sidewall 11a and the chassis sidewall 17, respectively. Specifically, the support pins 12 and 21 are respectively engaged with a slot 11b provided in the holder sidewall 11a and a slot 17a provided in the chassis sidewall 17 in a slidable manner.
The slot 17a extends along a longitudinal direction of the chassis sidewall 17. As shown in FIG. 8B, the pin insertion hole 17b is provided at the center of the upper side of the slot 17a, such that the slot 17a and the pin insertion hole 17b are connected. The pin insertion hole 17b is large enough to allow the support pin flange 22 to pass therethrough. On the other hand, a width of the slot 17a excluding the pin insertion hole 17b is narrower than a diameter of the support pin flange 22. As shown in FIG. 8C, the support pin boss 20 of the arm 15 is narrower than the width of the slot 17a and is engaged with the slot 17a so as to be slidable along the longitudinal direction of the slot 17a. 
Thus, as shown in FIG. 8B, when aligning the support pin 21 with the pin insertion hole 17b and pushing the arm 15 in a direction normal to the sheet of FIG. 8B, the support pin flange 22 passes through the pin insertion hole 17b so that the support pin flange 22 is external to the chassis sidewall 17. Thereafter, as shown in FIG. 8C, by moving the support pin 21 downward and transversely along the slot 17, the support pin boss 20 is engaged with the slot 17a. 
In a subsequent step of assembly of the conventional cassette loading device, as shown in FIG. 8A, the pin insertion hole 17b is covered by a frame 19a of a cassette slip prevention element 19. This prevents the support pin 21 from being disengaged from the slot 17a during operation when the cassette holder 11 is moved up and down.
However, in the above conventional structure, the following problems described below occur.
When the support pin flange 22 is positioned at the end of the slot 17a shown in FIG. 8B by a dashed circle, the cassette holder 11 is in an uppermost position of its moving range. When the pin flange 22 is positioned at the other end of the slot 17a, the cassette holder 11 is in a lowermost position of its moving range.
Accordingly, in order to assemble the cassette loading device with the chassis sidewall 17, it is necessary to align the support pin 21 with the pin insertion hole 17b while keeping the cassette holder 11 in a suitable position between the uppermost and lowermost positions of its moving range. This results in the assembly of the conventional cassette loading device being difficult and time-consuming.
Moreover, after the support pin 21 has been inserted into the slot 17a via the pin insertion hole 17b, a cover member is required to cover the pin insertion hole 17b so as to prevent the support pin 21 from being disengaged from the slot 17a during operation, e.g., the frame 19a of the cassette slip prevention element 19. As a result, the number of parts used for the conventional cassette loading device is increased.